Re: [v6ops] Deprecating 2002::/16

On Thu, 7 Apr 2011, Dmitry Anipko wrote:

> Hi Pekka,
>
>>> When connecting to a dual-stack server with IP addresses 2.2.2.2 and
> 2001:db8::1.It will use 6to4 instead of IPv4 through NAT. FAIL.
>>>  2) 6to4 is used if v4 has mismatching scope (private->public)
>
> Windows implementation treats RFC 1918 prefixes as public, specifically 
> due to this reason, so on Windows, in this scenario v4->v4 is preferred 
> over 6to4->native v6.

Same for FreeBSD, OpenBSD and NetBSD.

>
> Thank you,
> Dmitry
> -----Original Message-----
> From: v6ops-bounces@ietf.org [mailto:v6ops-bounces@ietf.org] On Behalf Of Pekka Savola
> Sent: Thursday, April 07, 2011 12:44 AM
> To: Christopher Palmer
> Cc: v6ops@ietf.org; Carlos Martinez-Cagnazzo
> Subject: Re: [v6ops] Deprecating 2002::/16 - 6to4 Historic Status
>
> On Thu, 7 Apr 2011, Christopher Palmer wrote:
>> "A host with a public but natted v4 address will alwas get hosed by this."
>>
>> A host in that condition will have a broken 6to4 address, but won't experience a degradation in their web experience if they have RFC 3484 implemented.
>>
>> So really this would be the third proposed 6to4 mitigation:
>>
>> 1. Ensuring that IPv4->IPv4 is ranked higher than 6to4->IPv6 in the RFC 3484.
>> 2. Changing default host behavior. (still being debated)
>> 3. Deprecation of the prefix.
>>
>> Given (1) and (2), the operational value of 3 is still lost on me. Is the expectation that ISPs stop routing 6to4 packets? Is this a signal that we don't just hate 6to4, but we super hate it?
>
> This will require an update in the RFC 3484 implementation.  Maybe
> this is what you meant, or maybe not.
>
> Joel is probably referring to this:
>
> http://tools.ietf.org/html/draft-ietf-6man-rfc3484-revise-02#section-2.4
>
> (This issue has a lot of history -- known for some 7-8yrs, see
> http://tools.ietf.org/html/draft-ietf-v6ops-v6onbydefault-03#section-2.1)
>
> If I understand this correctly:
>
> The NAT44ting/6to4 gateway has public IP 1.1.1.1 (WAN)
> It is advertising 2002:0101:0101:0::/64 out on LAN.
> It is doing NAT on LAN.
>
> Hence, hosts behind such gateway have IPv6 address
> 2002:0101:0101:0::EUI64 and 192.168.1.1.
>
> When connecting to a dual-stack server with IP addresses 2.2.2.2 and
> 2001:db8::1.
>
> It will use 6to4 instead of IPv4 through NAT. FAIL.
>
> If the client would have had IP address 1.1.1.2 and
> 2002:0101:0101:0::EUI64, with (current) RFC3484 implementation, it
> would have preferred IPv4 instead of 6to4.
>
> So, there are are really two layers of RFC3484 brokenness:
>
>  1) not implemented at all
>  2) 6to4 is used if v4 has mismatching scope (private->public)
>
> -- 
> Pekka Savola                 "You each name yourselves king, yet the
> Netcore Oy                    kingdom bleeds."
> Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
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